Difference between revisions of "Detector Rates and Lifetime"
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==== PMT specifications ==== | ==== PMT specifications ==== | ||
| − | According to the specifications for the Hamamatsu PMT H9779 (8-stage) the maximum operating current is 100 nA. Elton estimated the signal amplitude based on this maximum current assuming a gain of 5*10^5 and 50ns signal base line. This results in an amplitude of 50mV. From bench tests with an LED on an H10534 PMT assembly with a 10-stage H9779 PMT | + | According to the specifications for the Hamamatsu PMT H9779 (8-stage) the maximum operating current is 100 nA. Elton estimated the signal amplitude based on this maximum current assuming a gain of 5*10^5 and 50ns signal base line. This results in an amplitude of 50mV. From bench tests with an LED on an H10534 PMT assembly with a 10-stage H9779 PMT and operating voltage of 1900V resulting in a gain of 4.1*10^6 and a measured 270 photo electrons per LED pulse a signal amplitude of 1.45V was recorded. The signal base line was about 20ns. |
Revision as of 10:17, 18 March 2011
As the rates close to the photon beam line can be substantial it is necessary to investigate the consequences on the performance and lifetime of the scintillator itself and its readout devices.
Rate Estimates
The estimated rates in a given paddle depend on the upstream detector geometry and target material. Some estimates can be found in GlueX-DB 994. In figure 2.1 of this document you find the estimated rates for all the long paddles. Not included are the half paddles needed for the beam whole cut-out. For the current geometry at that time rates of up to 3MHz for the inner most paddles are expected at 10^8 photons/s (coherent peak). As the Monte Carlo and detector geometry might have changed substantially over the last 3 years it might be prudent to redo these calculations.
PMT specifications
According to the specifications for the Hamamatsu PMT H9779 (8-stage) the maximum operating current is 100 nA. Elton estimated the signal amplitude based on this maximum current assuming a gain of 5*10^5 and 50ns signal base line. This results in an amplitude of 50mV. From bench tests with an LED on an H10534 PMT assembly with a 10-stage H9779 PMT and operating voltage of 1900V resulting in a gain of 4.1*10^6 and a measured 270 photo electrons per LED pulse a signal amplitude of 1.45V was recorded. The signal base line was about 20ns.
